136 ESSAYS ON BACTERIOLOGY. 



commonly held to be the probable cause of malaria, 

 are not classified among the bacteria, yet their study is 

 so closely associated with bacteriology that reference 

 may properly be made to them here as in all recent 

 works on this subject. The malarial plasmodia are 

 protoplasmic bodies, varying in size and shape, often 

 pigmented, and to be found, most frequently during 

 or near the time of a paroxysm, in the blood of one 

 suffering from ague. They have not been success- 

 fully cultivated oiitside the body; final demonsti-ation 

 of their character and specific causative agency is 

 therefore still lacking. JSTevertheless they are so con- 

 stantly associated with the disease, and in such a sig- 

 nificant way, that their presence is now generally held 

 to afford ground for positive diagnosis, and therefore 

 for a clinical distinction between this and other dis- 

 eases. Bedside experience is constantly confirming 

 this belief. In obscure cases the examination of the 

 blood has come to be relied upon by the highest clin- 

 ical authorities. This examination, though at times 

 tedious, is not at all difficult. Puncture of the lobe 

 of the ear, or the finger, yields the droplet of blood, 

 which is transferred to the cover glass and immedi- 

 ately examined unstained. The blood specimen may 

 also be examined after staining with methyl blue, hav- 

 ing first been simply mixed with the dye or dried and 

 heated by the ordinary method; or, much better, fixed 

 by prolonged heating or by immersion in equal parts 

 of alcohol and ether. Counter-staining may be done 



